/*!
 * Lazy Load - jQuery plugin for lazy loading images
 *
 * Copyright (c) 2007-2015 Mika Tuupola
 *
 * Licensed under the MIT license:
 *   http://www.opensource.org/licenses/mit-license.php
 *
 * Project home:
 *   http://www.appelsiini.net/projects/lazyload
 *
 * Version:  1.9.7
 *
 */

(function($, window, document, undefined) {
	var $window = $(window);

	$.fn.lazyload = function(options) {
		var elements = this;
		var $container;
		var settings = {
			threshold       : 0,
			failure_limit   : 0,
			event           : "scroll",
			effect          : "show",
			container       : window,
			data_attribute  : "original",
			skip_invisible  : false,
			appear          : null,
			load            : null,
			placeholder     : ""
		};

		function update() {
			var counter = 0;

			elements.each(function() {
				var $this = $(this);
				if (settings.skip_invisible && !$this.is(":visible")) {
					return;
				}
				if ($.abovethetop(this, settings) ||
					$.leftofbegin(this, settings)) {
					/* Nothing. */
				} else if (!$.belowthefold(this, settings) &&
					!$.rightoffold(this, settings)) {
					$this.trigger("appear");
					/* if we found an image we'll load, reset the counter */
					counter = 0;
				} else {
					if (++counter > settings.failure_limit) {
						return false;
					}
				}
			});

		}

		if(options) {
			/* Maintain BC for a couple of versions. */
			if (undefined !== options.failurelimit) {
				options.failure_limit = options.failurelimit;
				delete options.failurelimit;
			}
			if (undefined !== options.effectspeed) {
				options.effect_speed = options.effectspeed;
				delete options.effectspeed;
			}

			$.extend(settings, options);
		}

		/* Cache container as jQuery as object. */
		$container = (settings.container === undefined ||
			settings.container === window) ? $window : $(settings.container);

		/* Fire one scroll event per scroll. Not one scroll event per image. */
		if (0 === settings.event.indexOf("scroll")) {
			$container.on(settings.event, function() {
				return update();
			});
		}

		this.each(function() {
			var self = this;
			var $self = $(self);

			self.loaded = false;

			/* If no src attribute given use data:uri. */
			if ($self.attr("src") === undefined || $self.attr("src") === false) {
				if ($self.is("img")) {
					$self.attr("src", settings.placeholder);
				}
			}

			/* When appear is triggered load original image. */
			$self.one("appear", function() {
				if (!this.loaded) {
					if (settings.appear) {
						var elements_left = elements.length;
						settings.appear.call(self, elements_left, settings);
					}
					$("<img />")
						.one("load", function() {
							var original = $self.attr("data-" + settings.data_attribute);
							$self.hide();
							if ($self.is("img")) {
								$self.attr("src", original);
							} else {
								$self.css("background-image", "url('" + original + "')");
							}
							$self[settings.effect](settings.effect_speed);

							self.loaded = true;

							/* Remove image from array so it is not looped next time. */
							var temp = $.grep(elements, function(element) {
								return !element.loaded;
							});
							elements = $(temp);

							if (settings.load) {
								var elements_left = elements.length;
								settings.load.call(self, elements_left, settings);
							}
						})
						.attr("src", $self.attr("data-" + settings.data_attribute));
				}
			});

			/* When wanted event is triggered load original image */
			/* by triggering appear.                              */
			if (0 !== settings.event.indexOf("scroll")) {
				$self.on(settings.event, function() {
					if (!self.loaded) {
						$self.trigger("appear");
					}
				});
			}
		});

		/* Check if something appears when window is resized. */
		$window.on("resize", function() {
			update();
		});

		/* With IOS5 force loading images when navigating with back button. */
		/* Non optimal workaround. */
		if ((/(?:iphone|ipod|ipad).*os 5/gi).test(navigator.appVersion)) {
			$window.on("pageshow", function(event) {
				if (event.originalEvent && event.originalEvent.persisted) {
					elements.each(function() {
						$(this).trigger("appear");
					});
				}
			});
		}

		/* Force initial check if images should appear. */
		$(document).ready(function() {
			update();
		});

		return this;
	};

	/* Convenience methods in jQuery namespace.           */
	/* Use as  $.belowthefold(element, {threshold : 100, container : window}) */

	$.belowthefold = function(element, settings) {
		var fold;

		if (settings.container === undefined || settings.container === window) {
			fold = (window.innerHeight ? window.innerHeight : $window.height()) + $window.scrollTop();
		} else {
			fold = $(settings.container).offset().top + $(settings.container).height();
		}

		return fold <= $(element).offset().top - settings.threshold;
	};

	$.rightoffold = function(element, settings) {
		var fold;

		if (settings.container === undefined || settings.container === window) {
			fold = $window.width() + $window.scrollLeft();
		} else {
			fold = $(settings.container).offset().left + $(settings.container).width();
		}

		return fold <= $(element).offset().left - settings.threshold;
	};

	$.abovethetop = function(element, settings) {
		var fold;

		if (settings.container === undefined || settings.container === window) {
			fold = $window.scrollTop();
		} else {
			fold = $(settings.container).offset().top;
		}

		return fold >= $(element).offset().top + settings.threshold  + $(element).height();
	};

	$.leftofbegin = function(element, settings) {
		var fold;

		if (settings.container === undefined || settings.container === window) {
			fold = $window.scrollLeft();
		} else {
			fold = $(settings.container).offset().left;
		}

		return fold >= $(element).offset().left + settings.threshold + $(element).width();
	};

	$.inviewport = function(element, settings) {
		return !$.rightoffold(element, settings) && !$.leftofbegin(element, settings) &&
			!$.belowthefold(element, settings) && !$.abovethetop(element, settings);
	};

	/* Custom selectors for your convenience.   */
	/* Use as $("img:below-the-fold").something() or */
	/* $("img").filter(":below-the-fold").something() which is faster */

	$.extend($.expr[":"], {
		"below-the-fold" : function(a) { return $.belowthefold(a, {threshold : 0}); },
		"above-the-top"  : function(a) { return !$.belowthefold(a, {threshold : 0}); },
		"right-of-screen": function(a) { return $.rightoffold(a, {threshold : 0}); },
		"left-of-screen" : function(a) { return !$.rightoffold(a, {threshold : 0}); },
		"in-viewport"    : function(a) { return $.inviewport(a, {threshold : 0}); },
		/* Maintain BC for couple of versions. */
		"above-the-fold" : function(a) { return !$.belowthefold(a, {threshold : 0}); },
		"right-of-fold"  : function(a) { return $.rightoffold(a, {threshold : 0}); },
		"left-of-fold"   : function(a) { return !$.rightoffold(a, {threshold : 0}); }
	});

})(jQuery, window, document);